MCE::Mutex(3) User Contributed Perl Documentation MCE::Mutex(3)
NAME
MCE::Mutex - Locking for Many-Core Engine
VERSION
This document describes MCE::Mutex version 1.844
SYNOPSIS
use MCE::Mutex;
my $mutex = MCE::Mutex->new;
{
use MCE::Flow max_workers => 4;
mce_flow sub {
$mutex->lock;
# access shared resource
my $wid = MCE->wid; MCE->say($wid); sleep 1;
$mutex->unlock;
};
}
{
use MCE::Hobo;
MCE::Hobo->create('work', $_) for 1..4;
MCE::Hobo->waitall;
}
{
use threads;
threads->create('work', $_) for 5..8;
$_->join for ( threads->list );
}
sub work {
my ($id) = @_;
$mutex->lock;
# access shared resource
print $id, "\n";
sleep 1;
$mutex->unlock;
}
DESCRIPTION
This module implements locking methods that can be used to coordinate
access to shared data from multiple workers spawned as processes or
threads.
The inspiration for this module came from reading Mutex for Ruby.
API DOCUMENTATION
MCE::Mutex->new ( )
MCE::Mutex->new ( impl => "Channel" )
MCE::Mutex->new ( impl => "Flock", [ path => "/tmp/file.lock" ] )
MCE::Mutex->new ( path => "/tmp/file.lock" )
Creates a new mutex.
Channel locking (the default), unless "path" is given, is through a
pipe or socket depending on the platform. The advantage of channel
locking is not having to re-establish handles inside new processes and
threads.
For Fcntl-based locking, it is the responsibility of the caller to
remove the "tempfile", associated with the mutex, when path is given.
Otherwise, it establishes a "tempfile" internally including removal on
scope exit.
$mutex->impl ( void )
Returns the implementation used for the mutex.
$m1 = MCE::Mutex->new( );
$m1->impl(); # Channel
$m2 = MCE::Mutex->new( path => /tmp/my.lock );
$m2->impl(); # Flock
$m3 = MCE::Mutex->new( impl => "Channel" );
$m3->impl(); # Channel
$m4 = MCE::Mutex->new( impl => "Flock" );
$m4->impl(); # Flock
Current API available since 1.822.
$mutex->lock ( void )
$mutex->lock_exclusive ( void )
Attempts to grab an exclusive lock and waits if not available. Multiple
calls to mutex->lock by the same process or thread is safe. The mutex
will remain locked until mutex->unlock is called.
The method "lock_exclusive" is an alias for "lock", available since
1.822.
( my $mutex = MCE::Mutex->new( path => $0 ) )->lock_exclusive;
$mutex->lock_shared ( void )
Like "lock_exclusive", but attempts to grab a shared lock instead. The
"lock_shared" method is an alias to "lock" otherwise for non-Fcntl
implementations.
Current API available since 1.822.
$mutex->unlock ( void )
Releases the lock. A held lock by an exiting process or thread is
released automatically.
$mutex->synchronize ( sub { ... }, @_ )
$mutex->enter ( sub { ... }, @_ )
Obtains a lock, runs the code block, and releases the lock after the
block completes. Optionally, the method is "wantarray" aware.
my $val = $mutex->synchronize( sub {
# access shared resource
return 'scalar';
});
my @ret = $mutex->enter( sub {
# access shared resource
return @list;
});
The method "enter" is an alias for "synchronize", available since
1.822.
$mutex->timedwait ( timeout )
Blocks until obtaining an exclusive lock. A false value is returned if
the timeout is reached, and a true value otherwise. The default is 1
second when omitting timeout.
my $mutex = MCE::Mutex->new( path => $0 );
# terminate script if a previous instance is still running
exit unless $mutex->timedwait( 2 );
...
Current API available since 1.822.
INDEX
MCE(3), MCE::Core(3)
AUTHOR
Mario E. Roy, <marioeroyA ATA gmailA DOTA com>
perl v5.28.2 2019-07-28 MCE::Mutex(3)
mce 1.844.0 - Generated Tue Aug 20 15:23:55 CDT 2019